Earlier in the week, Aldrin tweeted about his doctor, who happened to be named David Bowie.

According to CNN, Aldrin was in the South Pole as part of a tourist group heading to the Amundsen-Scott South Pole Station through White Desert. Initially, the trip was expected to last through December 12.

Aldrin was reportedly transported and found to have fluid in his lungs, reported CNN, but responded well to treatments.

The evacuation was a “precautionary measure” decided on by a White Desert doctor and the US Antarctic Program doctor.